Rolf Zeller is Full-Professor in Anatomy and Embryology at the DBM Centre for Biomedicine, University of Basel. The main research topics of his group include genetic and systematic analysis of the signal-antagonist interactions and auto-regulatory feedback loops that control vertebrate organogenesis. In particular, mouse molecular genetics is used to analyse the BMP signal-antagonist interactions that control proliferation and survival of stem-cell progenitors and the specification of particular cell fates during progression of limb and kidney organogenesis (patterning and initiation of differentiation). More recently, an analysis of the potential roles of aberrant BMP and SHH signal-antagonist interactions in tumour initiation and progression has been initiated with particular emphasis on tumour-stroma cell interactions.